Gear cutting machine



April 27, 1965 A o. RoGG 3,180,228

GEAR CUTTING MACHINE Filed April 23. 1963 3 Sheets-Sheet l bis ATTORNEY April 27, 1965 o. ROGG 3,180,228

GEAR CUTTING MACHINE Filed April 23, 1963 3 Sheets-Sheet 2 l( 1/ (90 /77 y2 fz# [i2 INVENTR. OTTO ROGG BY IWICHAEL S. STRIKE/Q his AITOHNILY April 27, 1965 o. ROGG 3,180,228

GEAR CUTTING MACHINE Filed April 23, 1963 5 SheeS-'Sheeb 3 JNVENYDR OTTO Rocid B7' M/cA/AEL S. Sra/KEI? United States Patent 'C 3,180,228 GEAR CUTTEJG MAC Otto Rog Munich, Germany, assigner to Carl Hurth, Maschinen und Zahnradfabrilr, Munich, Germany Filed Apr. 23, 1963, Ser. No. 275,023 Claims priority, application Germany, Apr. 27, 1962, H 45,608 l2 flairns. (Cl, gil- 4) The present invention relates to gear cutting machines in general, and more particularly to an improved feed arrangement which brings about and which controls the depth feed (also called infeed) of the cutting tool relative to the work gear or vice versa. Still more particularly, the invention relates to an improved hydraulic feed arrangement for gear cutting machines and similar ma* chine tools wherein a Work support or slide is `moved relative to a tool support or vice versa.

lnk conventional gear cutting machines of which l have knowledge at this time, the feed arrangement normally comprises a double-acting hydraulic cylinder and piston unit wherein the maximal stroke of the piston equals the difference between the radii of greatest and smallest work gears for whose cutting the machine is intended, plus the maximal infeed stroke which the cutter must perform in the course of a cutting operation. Since the length of such strokes is often considerable, the volume of cylinder chambers is rather large which, in turn, often produces inaccuracies in feed. One reason for such inaccuracies is that oil (which is normally utilized as a pressure fluid in double-acting hydraulic units f feed arrangements for gear cutting machines) is not an ideal liquid because it can be compressed at elevated pressures. Such compressibility of oil is due to the presence of entrapped air which causes the oil to exhibit a certain degree of elasticity and such elasticity of oil brings about undesirable displacements of the work gear with respect to the cutting tool or vice versa and allows for certain inaccuracies in the cutting operation.

Accordingly, it is an important object of my invention to provide a novel feed arrangements for use in gear cutting machines and similar machine tools, and to construct the feed arrangement in such a way that the extent of uncontrolled movements of a workpiece relative to the tool or vice versa is negligible or that any such uncontrolled movements may be prevented in a very simple and eliicient manner.

Another object of the invention is to provide a feed arrangement which compensates for the elasticity of h draulic pressure fluid such as is yutilized to move the work relative to the tool or vice versa.

A further object of the invention is to provide a feed arrangement of the above outlined characteristics which, in addition to being operable by a hydraulic pressure fluid, may be actuated by a manually or automatically controlled mechanism so that the starting position and the stroke of the feed arrangement may be selected `at will.

A concomitant object of the invention is to provide a feed arrangement of the above outlined characteristics which, in addition to bringing about and regulating the infeed strokes of the tool relative to the workpiece or vice versa, may also initiate and control certain other operations, such as starting or arresting the machine tool, distributing lubricant to some or all moving parts of the machine, injecting cutting oil, and other functions.

Still another object of the invention is to provide a feed arrangement which embodies some or all of the above outlined features and advantages, and which may be rapidly and conveniently installed in existing machine tools without necessitating any or by necessitating mini- Cice mal alterations in the construction and/or mounting of the remaining components in such machines.

A concomitant object of the invention is to provide a feed arrangement for gear cutting machines which requires smaller quantities of hydraulic fluid to a reciprocate one of the slides in such machines so that the likelihood of uncontrolled movements owing to elasticity of the fluid is very remote and that the overall size, weight an initial cost of the feed arrangement may be reduced Without in any Way affecting its usefulness.

A further object of the invention is to provide a feed arrangement which is constructed and assembled in such a way that its hydraulically operated unit must produce comparatively short movements of parts which `are connected therewith, so that the length of such movements need not substantially exceed the length of actual infeed strokes and that the chambers of the hydraulic unit may be sealed by simpler and less expensive devices.

With the above objects in view, one feature of the invention resides in the provision of a feed arrangement which is utilized to move the tool support with respect to the Work support or vice versa, for example, to move the tool silde of a gear cutting machine an elongated path toward and away from the work slide or vice versa. The feed arrangement may comprise a motion transmitting member, such as a piston rod or a push rod, which is adjustably coupled to the support and which is preferably reciprocaole by a double-acting hydraulic cylinder and piston unit to reciprocate the support, and a device for adjusting the position of the support with respect to the motion transmitting member or vice versa, Such adjusting device may assume the form of a gear train which is operatively connected with the motion transmitting member and with the support, and which may be actuated manually oiiby a suitable motor, eg., a selsyn, a hydraulic motor or a pneumatic motor.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The feed arrangement itself, however, both as to its construction and its method of operation, together with additional features and advantages thereof, will be best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

HG. 1 is a perspective View of a gear cutting machine comprising a feed arrangement for the work slide which embodies one form of my invention;

FIG. 2 is an enlarged vertical section through the casing of the feed arrangement substantially as seen in the direction of arrows from the line Il-ll of FIG. 1;

FIG. Za illustrates a hydraulic or pneumatic motor which may be utilized to operate the adjusting device of the feed arrangement shown in FIG. 2;

FlG. 3 is a vertical section through the casing of a modified feed arrangement; and

FIG. 4 is a schematic diagram of a hydraulic control system for the feed arrangement of FIG. 3.

Referring now in greater detail to the drawings, and first to FIG. l, there is shown a gear forming machine (for example, a machine for cutting gears) which comprises a frame lil having a pair of spaced vertical guides 11 (only one shown in FIG. 1) defining an elongated straight path for a reciprocable tool support here shown as a hollow slide 12, and spaced horizontal guides 13, 13a also defining an elongated straight path for a reciprocable Work support 14 which also assumes the form of a hollow slide. The guides lll and 13, 13a may be disposed in a common plane or in parallel planes and are provided on the vertical front wall of the frame 10 to control the direction of reciprocatory movement of the slides 12, 14 in such a Way that these slides may travel in elongated paths which are inclined through degrees with reference to each other. Thel frame defines an internal chamber kwhich accommodates a. withdrawable chipcollecting pan or tray 15.

The upper portion `of the tool slide 12 accommodates an electric motor 18 which is theprime mover of the machine andwhich operates a V 4belt drive 19 including a pair of pulleys one of which drives a shaft 20` .whose front end `portion carriesa spur gear 21 forming'part of a speed change gear which includes; a second spur gear 21a meshing with the gear 21, a shaft 23 which is driven by the gear 21a, and a bevel gear 23a which is driven by the shaft 23. The speed change gear determines theitpin. of the tool. The bevel gear 23a, mates with a second bevel gear 23h which is mounted on and which drives a horizontal main kshaft 24 whose right-hand portion projects from the tool slide 12 and extends into a tool holder or carrier 25. This carrier is mounted on the tool slide 12 and is turnable about the axis of the main shaft -24 so that itl may be arrested by a suitable mechanism (not shown) in one or more positions of angular adjustment with respect to the slide 12.V

The main shaft 24 carries at its right-hand end a bevel gear 25 which mates with a second bevel gear26a mounted at one end of a shaft 27 which is rotatably mounted in the tool holder 25 and whose other end carries a pinion 28a. This pinionmeshes with a spur gear A28h which is mounted on thespindle 29 of a substantially Worm-shaped tool 38. In the illustrated embodiment, the tool 30 is assumed to be a hob That'end portion lof the tool 30 which is turned away from the spindle 29 is rotatably` supported in a suitable backrest, not shown The left-hand end portion of the main shaft 24 carries a removable spur gear 31a which forms part of a gear train constituting an index changergear which also includes gears 31h and 31'.' The latter gear is mounted on a horizontal shaft 32 lwhich forms part of a reversing gear This reversinggear includes a pair of spaced bevel gears 33, 34 which'are freely rotatable on the shaft 32- and which are in permanentmesh with a driven bevel gear 35 mounted at the upper end, ofa splined shaft 36a, anda clutch sleeve 36 which is driven by and Whichts slidable along the shaft '32 Each axial end of this sleeve 36 is provided with 'a set of jaws so that the sleeve may engage complementary jaws of thev gear 33 or 34 in order to drive the bevel gear 35 and the splined shaft 36a in a clockwise or antic-lockwise direction. The shifter leverwhichmoves the sleeve 36 along the shaft 32 into engagement with the jaws of the gear 33 or 34 is not shown in the drawings. The purpose of the reversing gear Y is ,to drive a work spindle 56 in a Yclockwiseor anticlockwise direction.

The lower end portion of the splined shaft 36a extends beyond theunderside of the tool-slide 12 and into a sta-Y second` bevel gear 39 mounted at the left-hand end of a worm shaft 40. The splined shaft 36a and the cylinder, 38 form part of adriving connection between the Vmain shaft 24 and the work spindle 50.' Since the cylindera38 is freely rotatable in the housing 37, and since the splinedk V.along the guidesll.

Themeans for `reciprocatingrthe tool slide 12 along the guides 11 comprises a worm 41 which is provided on the shaft 4l)4 andV which is located in the-housing'37 tovrnesh.

with Ya Vworniwheel 41a Vmounted ,on the input shaft 42 of a feed change gear. includes a gear rrain43 one element of which is mounted on the input shaft 42 and another element of which drives This feed change gear further a second worm shaft (not shown) provided with a worm which meshes with a worm 4wheel 44 located at the lowerl end of a vertical feed spindlev or screw 45. The upperportion of the screw 45 projects into the tool slide 12 and meshes with an internally threaded spindle nut 46 which" is rigidly mounted in the tool slide so thatrotary movements of the screw 45 in a clockwise: or anticlockwise: direction compel therslide 12 to move up and down alongy its guides 11. The base47 serves as a rigid support for the casing 37 and screw 45 to hold the casing in position when the work slide moves along the guides 11.

The right-hand portion'of the worm shaft 40 is splined is compelled to share all rotary movements of the worm shaft 40. The worm 48 drives a worm wheel 49 which is secured to androtates the work spindle 50. The head 51 of the spindle 50 is located at a level above the-upper'. side ofthe work slide 14 and indirectly supports the work gear 52 in a manner not forming part of this invention so v that thework gear may be engaged by the tool 30. The slide 14 jcarries4 a column 53supporting a headstock 54 which may be f provided with means for engaging ythe upper end face ofthe work gear 52 in a manner not forming part of this invention.

The heretofore vmentioned parts of the gear shaping machine were described in detail solely for the purpose of facilitating theunderstanding of the present invention which resides in the provision of, an arrangement for imparting feed movements to one of the slides, in the present instance to the work slide,14,i.e., forv causing the workl gear 52 to move radially of and toward or away from the tool 30 in response to movements of the slide 14 along the guidesl, 13a. Such feed movements must be carried out; to ,adjust the machine.V in the event that the;

machine is convertedfrom shaping of one type of Awork gears to the shaping of another type of work gears. Certain parts of the novel feed arrangement are mounted in a fixed casing 61 which'issupported by and which its-bolted to Vthe machine frame 10 at a level above the pan 15.

FIG; 2 illustrates one embodiment of my improved feed arrangement-'furthe work slide;14,and is a vertical secy tion through the casing 61. The casing e1 accommodates or is integral with a cylinder 62 fora double-acting piston 63 which is provided with sealing rings 64, 55 and which divides the internal space of the cylinder 62 rinto a pair of separate cylinder chambers 86,87'. The piston 63 is rigid with a coaxial vmotion-transmitting piston Vvrod..66'

which is heldfagainst rotation by but which is axially movable with a key 69 provided in an annular attachment 61a which is xedly secured to the right-hand end portion of the casingy 61, as Viewed in FIG. 2. The axis of the piston rod 66 is parallel with the path defined bythe guides 13,

13a; This' piston rod is surrounded by annular sealing rings 67,68 which prevent leakage of pressure .fluid from the internalspace of the cylinder 62. The left-hand end portion 79 ofthe piston rod 66 constitutes a spindle and is provided with external threads to matewith an internally j threaded elementhere shown as a spindle nut '71;V the latter f is rotatable in a portion of the Work slide 14 butis held against axial movements with respect thereto so that the work slide isv compelled to shareV all axial movements of t the piston 63,*y and v.of the'motion-transmitting pistonr rod 66. The spindlenut 71 is rigid-with a worm Wheel72' which mates with a worm 73 yprovided ona worm shaft 74 which extends forwardly and through the front Wall of the work'slide 14 so that its exposed end portion 75 of non-circular lshape which constitutes the actuatingk means of theadjustmg device may be engaged by a suitable .tool

which is utilized to manually adjust the position of the v work slide with respect to the ,piston Vrod 66 (and hence,

with respect to the piston -63).i.e., for moving the work alsmaar;

75 of the worm shaft 74 may be rotated by a reversible electric motor, such as a selsyn 75a (shown in. phantom lines), or by a reversible hydraulic or pneumatic motor 75h (see FIG. 2o). It will be readily understood that the transmission represented by the parts 72-'74 may be replaced by another type of transmission, for example, by a train of meshing spur gears or the like or by a transmission which is otherwise coupled to the spindle nut 71, as long as such transmission can adjust the axial position of the work slide 1d with respect to the piston rod 66.

The other end portion of the piston rod do is also provided with external threads, as at '76, to mesh with an axially adjustable stop member here shown as a nut 77 which may be fixed in selected positions of adjustment by a radial screw 7S, preferably through the intermediary of a friction-producing plug 79 which is biased by a helical spring 79a.

rflic length of axial strokes of the piston rod do is regulated by adjustable stop means including the attachment 61a and the nut 77 and having two pairs of stop faces including a first stop face Sil provided on the fixed attachment 61a and cooperating with a stop face 81 on the nut 77, and a second stop face 32 on the attachment 71a which cooperates with the face S3 of a second stop member here shown as a fixed ring 84 which bears against an annular shoulder 66a of the piston rod '66. This ring S4 is provided in the right-hand chamber 87 of the cylinder o2 to the right of two arresting nuts 63a which cooperate with an annular collar @ab to hold the piston 63 against axial movement with respect to the piston rod. It will be noted that the stop faces Sti-d1 and S12-83 determine and regulate the extent of radial infeed movement of the work gear 52 with respect to the tool 3u.

The casing di preferably supports or accommodates one or more electric switches which control certain operations of the machine while the piston rod 66 performs or at the time the piston rod reaches the one or the other end of its strokes. One such switch 85 is shown in the attachment ein, and it will be noted that the trip 85a of this switch will be engaged by the stop nut 77 at the time the piston rod 66 reaches the left-hand end of its stroke to feed the work gear 52 in a direction radially of and toward the tool 36. The switch S5 may serve to automatically arrest the motor 18 when its trip 85a is engaged by the stop nut 77.

The cylinder o2 is formed with ports 36a, 87a which respectively communicate with the chambers 85, 87 and with suitable conduits which latter serve as a means for selectively admitting a pressure iiuid into or for evacuating spent fluid from the respective cylinder chambers. The source of pressure fluid, the pump means which compresses the fluid, and the reversing valve which selectively admits pressure duid to the chamber 86 while permitting escape of fluid from the chamber 87 or vice versa are not shown in the drawings. Such hydraulic control means for a double-acting cylinder and piston unit are well known and by themselves form no part of this invention. l prefer to operate with oil or with a similar liquid pressure medium. The absolute length of strokes which the piston rod 66 (and hence the work gear 52) should perform is normally slightly greater than the depth of the gear teeth when the machine is used for cutting of gear teeth, and such length is determined by the distance between the stop face 33 of the ring 84 and the stop face 31 of the nut 77. The axial position of the nut 77 may be adjusted subsequent to loosening of the screw 78 to thereby change the distance between the stop faces S1, 33. Adjustments in the angular position of the worm shaft '7d will change the position of the work slide 14 with respect to the piston rod 66 so that the work slide may change the position of the work gear 52 radially of the tool 30 by responding to rotation of the worm shaft 74 or by following axial movements of the motion-transmitting piston rod 66 in response to admission of pressure fluid into the chamber So or S7.

liO

In FIG. 2 the position of the adjusting device 7i-75 yis angularly displaced through degrees with reference to a position corresponding to that of FIG. l. This was done for the sake of clarity.

The advantages of a feed arrangement which embodies the adjusting device 71-75 may be summarized as follows: The stroke of the piston 63 must exceed only slightly the maximal infeed stroke, i.e., a distance which corresponds to the radial distance between the end face and the root of a gear tooth or the maximal depth of a tooth space. All other feed movements of the slide l@ may be initiated by the adjusting evice '7l-75 which is operated when the machine is converted for cutting of a different set of gears whose diameters are greater or smaller than that of the gear 52. Consequently, the cylinder chambers 86, 87 may be rather small and the quantity of oil used to reciprocate the piston d3 is also less than in conventional gear cutting machines. Obviously, such small amounts of oil are less likely to contain substantial quantities of entrapped air which would render the oil elastic and which could cause inaccuracies in feed movements of the work slide. When the gear cutting machine is in actual use, the adjusting device 71-75 is idle and all feed movements of the work slide 1d are initiated by the hydraulic cylinder and piston unit 62-63.

FlG. 3 illustrates a different construction of the feed arrangement for a slide which may be a tool slide or a work slide. In this embodiment of my invention, the casing E61 (which corresponds to the casing 6l of FIGS. l and 2) again comprises an attachment 161:1 which is similar to the attachment ola and whichis provided with two stop faces 18), 132; respectively cooperating with stop faces 181 (provided on a stop nut 177 which is screwed onto and which is axially adjustable along the right-hand end portion 176 of a motion transmitting member 156 which corresponds to the piston rod 66) and 183, the latter being provided on a stop ring 1%54 which is fixed to the member 156.

The casing 161 accommodates a two-piece cylinder 162A, 162B which receives the end portions of a reciprocable piston 9d; such end portions extend respectively into cylinder chambers 9i?, 97 which are connected with suitable conduits shown in FIG. 4. The means for reciprocating the motion transmitting member in response to reciprocation of the piston 9d comprises a two-armed lever 95 which is rockable about a stationary pin 93 fixed to the casing 161 and whose longer arm 95a is connected to the piston 9d by a diametral pin 95h in such a Way that the pin 95h may slide in an elongated slot of the longer arm. The shorter arm 94 of the lever 95 is coupled to the motion transmitting member 166 by a connection 92 of 'any known design so that the member 166 performs axial movements in response to rocking of the lever 95 about the fixed pin 93. The left-hand end portion 17? of the member 16o is provided with external threads to mate with a spindle nut 71 (not shown) in the same way as described in connection with FIG. 2, and such spindle nut is again rotatable by a gear train or the like to adjust the position of the slide which is adjustably coupled to the member 16o. Thus, the slide which is coupled to the member may be reciprocated either by admitting pressure fluid into the chamber 96 or 97, or by changing the axial position of the nut which meshes with the end portion 170.

The internal space of the casing 161 accommodates a pair of electric switches 98, 99 which are disposed at the opposite sides of and which may be tripped by the longer arm 95a of the lever 95 when the latter is caused to rock about the pin 93. In this embodiment of my invention, the piston @il also serves as a means for initiating injection of lubricant at selected intervals to all or to some parts of the machine in which the feeding means of FIG. 3 is mounted. As shown, the longer arm 95a of the lever 95 may rock a bell crank lever itil which is tiirnable about a fixed pin 191e: and which controls a lubricating device so that this lubricating device discharges one or more jets of lubricant whenever thelever 95 is caused to rock in a clockwise direction. `It will be,v

the lever'ltll may be dispensed with.'Y It isalso possible to provi-de an operative'connection between thetlubricatmg l deice 1li@ and the piston 96 or the motion transmitting member 16e.' Y

As explained hereinabove, the feed arrangement of FGQZ or 3 may be utilized with equal advantageto re-` ciprocatevthe tool slide 12,or themachine may comprise two such feed arrangementaione 'for each slide.

An important advantage of the just described feed arrangement is that the length of strokes performed by the piston 9d may exceed substantiallyfthe length of strokes performed' by the motion transmitting member L66. Therefore, the piston 99 may be one of smalldiameter and may be sealed in a very simple manner'.v Also, the chambers 96, 97 are very small in comparison with'cylinder vchambers of known feed arrangements so that they likelihoodk that entrapped air bubbles would render the oil elastic is very remote and the feed movement'is eX'- ceptionally accurate in all stagesof gear cutting operation. The lever 95 transforms longaxial movements of the piston VQtiinto much shorter feed movements of theY member 165 such as are necessary to feed the work gear toward the tool or vice versa, depending upon whether' the member v is coupled to the work slide or to the tool slide.

FIG. 4 shows the hydraulic control systemfor the feed arrangement of FIGS. A Y

Pumps 204, 2&5 which are driven by an electric motor 206 draw iluid from an oil-container 291 through strainers 262, 263 and deliversuch fluid to a solenoid operated four-way valve 213 having solenoids 214.-, 214.V The uid flows through a flow control valve 216 and into the cylinder chamber 96. The valve 216 insures that the uid iiows at a constant rate independently of its viscosity. Ther chamber' 97 discharges spent uid through a reaction valve 219 which'comprises an adjustable spring 26S and which maintains `such spent fluid underk a predetermined pressure, depending on the momentary bias of the spring S.V In response to admission of iluid into the chamber 96,' the piston 99 moves in a direction to the left, as Y viewed in FIG: 4, and rocks the lever g5 in a clockwise direction so that the vwork slide 214 moves in the direction indicated by an arrow 214a. Such movement of the work slide is arrested by the stop facelSil. At the same time, the longer arm 95a of the lever 95 trips the switch 99 so that the latter terminates the driving connection between the pump 295 and the motor 286. A pressure switch 27 is responsive to sudden increases in pressure prevailing in the chamber 96 when theworkslide 214 is arrested at the time thestop face 185i prevents further feed movement. Such 'sudden increase in pressure which prevails in the chamber 95 is used to actuate a clamping device 222 for the work slide, and this clamping device is actuated by aV sequence valve 218 which comprisesa spring l211'V thery advancei of the work slide, the switch 98 starts theV pump 205 and the operation of Vthe feed arrangement is d then repeated in the same wayas described-hereinabove.

-FIG.` 4` also shows certain other elements ofthe con- Vtrol system-including van unloading valvew20`9 forv the If the' solenoid operated .valve pumps 204, 265 which includes a solenoid 21'07and a spring 211, a filter-12151 which is mounted in the Ureturn,

conduit connecting the 7valve 213Y with the .oil container, and two additional check valves 212, 212"... Thereturn conduits are shown by broken lines. The system'of valves shown in FIGLA Vforrnsno part of my :invention and has been illustrated solely lfor the purpose of showing how the switches 9899 may initiate automatic operations:

in response to movements of the work slide. f

A machine which is provided with a feed arrangement of the type described in connection with FIG. 2 `or/3 may be used with great advantage in automatic gearv cutting machines, which are intended `for mass-manufacture ofv gears, i.e., Whichperfo'rm without manualy control a yseries ofmovements including receiving a blank, carryingoub the gearcuttng operation, discharging the finished gear, receiving ka new Iblankyetc.

controlled controlv unit or the like.

part of this invention. Foriexample, the control unit may Vcomprise a punched tape with prerecorded program, a tape sensing device including a bank of pins, and a con= trol device which regulates theselsyn.

Of course, the-just mentioned vselsyn may .befreplaced Vby' a suitable hydraulic motor, 'and the operative connection which actuates;the hydraulic motor at selected intervals is then modified accordingly. Such hydraulicmotor lof the aforementioned selsyn may operate the adjusting device, whereas the hydraulic unitv which .controls the motion transmitting member 66 or 166 may be operated in :accordance with` any heretofore known p-rocedure.

Without further analysis, the foregoing Vwill so fully reveal the gist of the present invention that others' can ,by

applying current knowledge, readily adapt it for Various applications without omitting features that, from the` standpoint of prior art, fairly rconstitute ,essential char,- acteristics of the` generic andspecic aspects of this invention and,.therefore, such adaptations should and are in-f tended to be comprehended within .the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1.7In a machine tool, in combination, guide means;de-.

ning an elongated path;A a slide :mounted on said guide means and reciprocable in said path; and a feed arrangesv ment for said slide, said` arrangement comprising a fixed cylinder, a double-acting vpiston reciprocably receiveddn said cylinder, a motion transmitting member arranged toy move in a direction parallel with said path, a lever ar-`4 ranged to pivot about ka ixedaxis and having a longer arm articulately connected with said piston and a shorter arm articulately connected ywith said motion transmitting member so that thev latter performs shorter strokes in response f to longer strokes of said piston, said motion transmitting |member comprising ya threaded portion constituting 1a l. spindle, and an adjusting device for moving said slidei with respect to said motion transmitting member and for alternatively transmitting reeiprocatory movements of said motion transmitting member to said slide, said adjusting device comprising a nut mating with said .spindle and` rotatably secured' to said slide, and actuating means mounted onsaid slide and drivingly; connectediwith said4 nut whereby the slidefis moved relative to said motionv transmitting Vmember in response torotation ofsaid nut and the slide moves with themotion transmitting member in response to reciprocation ofsaid piston.

r2. In a machine tool, in combination, guide meansde-` fining an'elongated path; a slide mounted on said guide means and'reciprocable in said pathyand a -feed arrangement for Isaid slide, said arrangement comprising a tixedcylinder, a double-acting piston reciprocably received in said cylinder, a motion-transmitting member -arrangedto move in a direction parallel with said pathand operatively connected with said piston so as to reciprocate in response to reciprocation of the piston, said motion transmitting member comprising a threaded portion constituting a spindle, adjustable stop means arranged to regulate the extent of reciprocation of said motion transmitting member in response to reciprocation of said piston, said stop means comprising a fixed attachment having a pair of spaced stop faces, a first stop member fixed to said motion transmitting member and arranged to -abut against one of said stop faces when the motion transmitting member moves in one direction, and a second stop member adjustably fixed to said motion transmitting member and arranged to abut against the other stop face when the motion transmitting member moves in the opposite direction and an adjusting device for moving said slide with respect to said motion transmitting member and for alternatively transmitting reciprocatory movements of said motion transmitting member to said slide, said adjusting device comprising a nut mating with said spindle and rotatably secured to said slide, and actuating means mounted on said slide and drivingly connected with said nut whereby the slide is moved relative to said motion transmitting member in response to rotation of said nut and the slide moves with the motion transmitting member in response to reciprocation of said piston.

3. A combination as set forth in claim 2, wherein said stop means comprises a xed attachment having a pair of spaced stop faces, a first stop member fixed to said motion transmitting member and arranged to abut against one of said stop faces when the motion transmitting member moves in a first direction, and a second stop member adjustably fixed to said motion transmitting member and arranged to engage the other stop face when the motion transmitting member moves in the opposite direction, said motion transmitting member comprising a second threaded portion and said second stop member being a nut meshing with said second threaded portion.

4. In a gear cutting machine, in combination, guide means defining an elongated path; a slide mounted on said guide means and reciprocable in said path; and a feed arrangement for said slide, said feed arrangement cornprising a fixed cylinder, a double-acting piston reciprocably received in said cylinder, said piston being spaced from and having an axis parallel with said path, a motion transmitting member arranged to move in a direction which is parallel to said path, connecting means coupling said motion transmitting member to said slide, and a lever arranged to pivot about a fixed axis and having a longer arm articulately connected with said piston and a shorter arm articulately connected with said motion transmitting member so that the motion transmitting member performs shorter strokes and moves the slide in said elongated path in response to longer strokes of said piston.

5. A structure as set forth in claim 4, wherein said motion transmitting member is an elongated rod.

6. A structure as set forth in claim 4, further comprising adjustable stop means for regulating the extent of reciprocation of said motion transmitting member in response to reciprocation of said piston.

7. A structure as set forth in claim 4, wherein said motion transmitting member 4and said lever together constitute a device for transmitting motion from said piston to said slide and further comprising electric switch means positioned in the path of and arranged to be actuated by said device in response to movement of said piston with reference to said cylinder, said electric switch means being provided to control at least one operation of said gear cutting machine.

8. A structure as set forth in claim 4, wherein said motion transmitting member comprises an externally threaded portion and wherein said connecting means comprises an internally threaded portion meshing with said externally threaded portion and secured to said slide, and actuating means for rotating one of said threaded portions so as to move said slide with reference to said motion transmitting member or vice versa independently of said piston.

9. A structure as set forth in claim 8, wherein said actuating means comprises a manually operated device for rotating said one threaded portion.

l0. A structure as set forth in claim 8, wherein said actuating means comprises an electric motor and an operative connection between said motor and said one threaded portion.

1l. A structure as set forth in claim 8, wherein said actuating means comprises a fluid-operated motor and an operative connection between said motor and said one threaded portion.

l2. A structure as set forth in claim 8, wherein said actuating means comprises a motor, an operative connection between said motor and said one threaded portion, and means for starting and arresting said motor in accordance with a predetermined schedule.

Reerences Cited by the Examiner UNITED STATES PATENTS 272,3 04 2/ 83 Muller. 1,067,139 7/ 13 Schellenbach. 1,206,086 11/16 Benjamin et al. 1,486,155 3 24 Morgan. 1,956,110 4/34 Turrettini 90-21.5 XR 2,069,701 2/ 37 Emmons 9021 2,332,365 10/43 Beebe 90-21.5 XR 2,338,737 I1/44 Purvin 90-4 2,83 8,825 6/5 8 Knollenberg.

FOREIGN PATENTS 669,342 4/ 5 2 Great Britain.

WILLAM W. DYER, JR., Primary Examiner. 

1. IN A MACHINE TOOL, IN COMBINATION, GUIDE MEANS DEFINING AN ELONGATED PATH; A SLIDE MOUNTED ON SAID GUIDE MEANS AND RECIPROCABLE IN SAID PATH; AND A FEED ARRANGEMENT FOR SAID SLIDE, SAID ARRANGEMENT COMPRISING A FIXED CYLINDER, A DOUBLE-ACTING PISTON RECIPROCABLY RECEIVED IN SAID CYLINDER, A MOTION TRANSMITTING MEMBER ARRANGED TO MOVE IN A DIRECTION PARALLEL WITH SAID PATH, A LEVER ARRANGED TO PIVOT ABOUT A FIXED AXIS AND HAVING A LONGER ARM ARTICULATELY CONNECTED WITH SAID PISTON AND A SHORTER ARM ARTICULATELY CONNECTED WITH SAID MOTION TRANSMITTING MEMBER SO THAT THE LATTER PERFORMS SHORTER STROKES IN RESPONSE TO LONGER STROKES OF SAID PISTON, SAID MOTION TRANSMITTING MEMBER COMPRISING A THREADED PORTION CONSTITUTING A SPINDLE, AND AN ADJUSTING DEVICE FOR MOVING SAID SLIDE WITH RESPECT TO SAID MOTION TRANSMITTING MEMBER AND FOR ALTERNATIVELY TRANSMITTING RECIPROCATORY MOVEMENTS OF 